Equipment for filtering a liquid

ABSTRACT

A description is given of equipment for filtering liquids, comprising three sections superimposed coaxially and placed above a container with filter walls for collecting the filtered particles. From the top to the bottom, the first section communicates directly with the second, while the second communicates with the third sector, and the latter communicates with the container via two valves. A pump introduces the liquid to be filtered into the first section, inside a filter layer, and another pump projects a quantity of the previously filtered liquid against the filter layer from the inside of the first section. By cyclically operating the valves it is possible to continuously filter the liquid, which flows out in the filtered state from ducts which branch from the first section, even while the particles deposited in the third section are discharged into a container with filter walls which is immersed in a vessel containing the liquid to be filtered.

[0001] The present invention relates to the technical field of equipmentwhich carries out the filtering and removal of solid particles containedin suspension in a liquid.

[0002] Such equipment is used in many industrial applications, includingfor example that of removing chips and impurities from the lubricatingand cooling liquid used in machining operations such as grinding,surfacing, etc.

[0003] In currently known equipment, designed and constructed in variousways, all the liquid filtered by the equipment is made to circulatethrough mechanical filters or cloths and the like, which have to beperiodically cleaned or removed with the filtered sludge, and theparticles which are concentrated in the filter area also have to beremoved periodically.

[0004] This requires repeated interruptions of the operating cycle,making it necessary to use two pieces of equipment in parallel,operating alternately, if it is desirable to filter continuously theliquid from a machine tool when it is undesirable, or impossible, tointerrupt the operation of the machine tool. The total cost of thecomplete filter equipment is therefore doubled.

[0005] Moreover, since the liquid to be filtered is projected underpressure against the filter surfaces, foreign bodies, sometimes ofconsiderable dimensions and mass, sucked up by the liquid circulationpump, frequently strike the filter surfaces violently and damage them.

[0006] The inventor of the present invention has devised equipment whichovercomes all the above drawbacks, owing to its particularconfiguration.

[0007] In this equipment, not all of the liquid from which particles insuspension have to be removed passes through a filter layer: some ofthese particles are permitted to settle under their own weight, so thatthey converge in a lower section of the equipment.

[0008] Additionally, some of the liquid which has already been filteredis used for planned continuous cleaning of the filter layer while theequipment is carrying out its work, and therefore the equipment does nothave to be stopped.

[0009] The aforementioned particles, when they have formed a mass ofpredetermined size, are transferred by gravity into an additionalunderlying section, where they are concentrated and from which they aresubsequently discharged into a container with filter walls immersed inthe vessel into which the liquid to be filtered is directed.

[0010] The passage of the particles from one section to the other, andfrom there towards the said container with filter walls, is achieved bythe cyclic opening and reclosing, with appropriate timing, of valvesthrough which, as is explained more fully below, the sections of theequipment communicate with each other and with the said container withfilter walls.

[0011] Equipment made according to the present invention can thereforebe used continuously, without stops.

[0012] The object of the present invention is therefore equipment asdescribed in the precharacterizing clause of the attached claim 1,characterized by what is disclosed in the characterizing clause of thesaid claim.

[0013] According to the teachings of the aforesaid claim 1, theequipment can be made in numerous different ways, according to theapplication; a preferred embodiment of the equipment is described below,with reference to the attached drawings, which show:

[0014] in FIG. 1, a schematic longitudinal section through the saidpreferred embodiment of the equipment according to the invention wherefiltering of a liquid is in progress;

[0015] in FIG. 2, the longitudinal section through the equipment of FIG.1, where the filtered particles which have accumulated in a section ofthe equipment are being removed while the filtering function continuesnormally.

[0016] With reference to both FIGS. 1 and 2, these show how equipment 1according to the invention consists of a plurality of sections 2, 6 and7 superimposed on each other coaxially, with their lowest endscommunicating with a container 9 with filter walls immersed in a vessel13 for the liquid 12 to be filtered.

[0017] First pumping means, consisting of a first pump 4 in thedrawings, draw up the liquid 12 to be filtered from the said vessel 13and send it under pressure to a first section 2 of the equipment 1,which is located at a higher level and is surrounded by a filter layer3, which in turn is surrounded by coaxial walls 2 p, located outside,and at a distance D from, the aforesaid filter layer 3.

[0018] Second pumping means, consisting of a second pump 5 in thedrawings, draw up a quantity of the liquid 12 which is already filteredas a result of having passed (arrows H) through the filter layer 3, andproject it under pressure, from the interior of the said first section2, towards the said filter layer 3 (arrows U), in such a way that thelayer is continuously cleaned and its holes are kept free of particleswhich could block them.

[0019] The remainder of the liquid 12 which has already been filteredpasses (arrow H) out of the said first sector 2 through one or moreducts 16 formed in the cavity with a thickness D, which is present, ashas been stated, between the filter layer 3 and the coaxial walls 2 pwhich surround it.

[0020] In order to make the said operation of cleaning the filter layer3 more efficient and functional, the said second pump 5 projects thesaid quantity of previously filtered liquid 12 towards the filter layer,through a device, for example a T-arm 17, with one or more horizontalsides 17 n, each provided with a nozzle 18 n, directed perpendicularlyagainst the said layer 3.

[0021] It should be noted that, in order to improve further the resultof the said operation of cleaning the filter layer 3, the liquid 12 tobe filtered is sent by the said first pump 4 into the first section 2from above (arrows N), in a parallel way and practically tangentially tothe said filter layer 3. This creates additional turbulence, whichfacilitates the work of removing the particles 11 i from the holes ofthe filter layer 3.

[0022] It is also preferable to provide the said T-arm 17 with means ofa known type 19 which can make it rotate (arrow A) and/or movevertically (arrow B) with an alternating movement while the saidcleaning operation is carried out.

[0023] The lower part of the said first section 2 is connected by itswalls 2 p to the walls 6 p of a second section 6, which is coaxial withthe first and preferably of truncated conical shape as shown, into whichthe particles 11 i contained in the liquid 12 flow by gravity (arrows L)without having to be retained by the filter layer 3. This is because theoperations of cleaning and remixing described above cause the particles11 i contained in the liquid 12 to continue to circulate between thefilter layer 3 and the area of the first section 2 lying within it,until the gravitational component pushes them downwards, in other wordsinto the said second section 6, where they accumulate.

[0024] A third section 7 is fitted below and coaxially with the saidsecond section 6, and is separated from it by means of a first valve 8,and this third section communicates downwards, through a second valve10, with a container 9 with filter walls immersed in a vessel 13 intowhich the liquid 12 to be filtered is introduced.

[0025] By suitable operation of the said two valves 8 and 10 while theequipment 1 is in operation, the results of continuity of operationmentioned above, and shown in the figures, are achieved.

[0026]FIG. 1 shows the equipment 1 in operation, with both pumps 4 and 5working, the first of these introducing the liquid 12 to be filteredinto the first section 2 while the second projects a quantity of thefiltered liquid against the filter layer 3.

[0027] The said first valve 8 is open, and the particles 11 i, whichsettle in the second section 6, are deposited and concentrated in theunderlying third section 7, which retains them because it is separatedbelow from the said container 9 by the second valve 10, which is closed.

[0028] On the other hand, FIG. 2 shows how, while all the members of theequipment 1 continue to operate, the first valve 8 has been closed, thusseparating the second sector 6 from the third sector 7 with a hermeticseal, and the second valve 10 has been opened, allowing the concentratedparticles 11 i to flow down by gravity into the said container 9 withfilter walls, which retains them and which can be removed when itcontains a predetermined quantity of them.

[0029] Clearly, the closing of the first valve 8 and the opening of thesecond valve 10 are carried out when the third section 7 has beensaturated with particles 11 i.

[0030] After the particles 11 i have been removed from the third section7 which contained them, the operation is repeated in reverse, the firstvalve 8 being reclosed to bring the equipment into the condition shownin FIG. 1. The operating cycle can therefore recommence from the start,without any need to stop the operation of the equipment 1 at any time.

[0031] Any foreign bodies introduced by the first pump 4 into the firstsection 2 fall rapidly, because of their weight, into the underlyingsecond section 6 and then into the third section 7, without interactingwith the filter layer 3, and can subsequently be removed together withthe particles 11 i when these are discharged into the container 9 whichretains them between its filter walls.

[0032] The equipment according to the invention can therefore be used toachieve all the objects identified by the inventor.

1. Equipment (1) for filtering and removing particles (11 i) containedin suspension by a liquid (12), characterized in that it comprises: afirst section (2) surrounded by a filter layer (3); a second section(6), delimited externally by walls (6 p) which are connected below towalls (2 p) which surround the said first section (2) and the saidfilter layer (3), which is spaced at a distance (D) from the filterlayer; a third section (7) placed coaxially with and underneath the saidsecond section (6), with which it communicates via a first valve (8); acontainer (9) with filter walls for collecting the sludge formed by thefiltered particles (11 i), placed under the said third section (7), withwhich it communicates via a second valve (10); a vessel (13) for theliquid (12) to be filtered, containing inside it the said container (9)with filter walls; first pumping means (4) which draw up the liquid (12)to be filtered from the said vessel (13) and introduce it under pressureinto the said first section (2); second pumping means (5) which draw upa quantity of the filtered liquid present between the filter layer (3)and the walls (2 p) which surround the said first section (2), andproject it against the said filter layer (3) from the inside of the saidfirst section (2); and one or more ducts (16) for the outflow of theremainder of the filtered liquid present between filter layer (3) andthe walls (2 p) which surround the said first section (2).
 2. Equipmentaccording to claim 1, in which the liquid (12) to be filtered isintroduced by the said first pumping means (4) into the said firstsection (2) from the top towards the bottom, in a parallel way andpractically tangentially to the walls of the said filter layer (3). 3.Equipment according to any one of the preceding claims, in which thesaid second pumping means (5) project the said quantity of the filteredliquid against the filter layer (3) through a device (17) provided withone or more outlet nozzles mounted on the ends of the same number ofarms (18 n) perpendicular to the filter layer (3).
 4. Equipmentaccording to claim 3, in which the said device (17) provided with outletnozzles (18 n) is supplied with means (19) which can make it rotateand/or move vertically with an alternating motion.